Optimization of pyroligneous acid production from palm kernel shell and its potential antibacterial and antibiofilm activities

Abstract

Oil palm plantation generates huge income to Malaysia. At the same time, huge amount of oil palm biomass is also generated which needs to be properly managed. Pyrolysis is one of the approaches available to utilize the oil palm biomass to produce biocharcoal, pyroligneous acid (PA) and bio-oil. PA was produced by condensing the pyrolysis gas emitted and have wide range of potential application including antibacterial activity and antibiofilm activity. In this study, we tried to optimize the operating pyrolysis condition for palm kernel shell to produce maximum yield of PA with highest total phenolic contents (TPC). The optimized PA fraction was evaluated for its antibacterial and antibiofilm properties. Optimum pyrolysis condition resulted in the production of PA containing highest TPC was determined to be at 526°C, heating rate of 10°C/min and nitrogen flow rate of 0.43 L/min. The inhibition zone of concentrated PA extracted by ethyl acetate (CPAE) was determined within 29.3-32.7 mm while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were in the range of 1.95-3.91 and 62.5-125 mg/mL, respectively. CPAE showed the capability to reduce biofilm formation by B. cereus, S. aureus, E. coli and P. aeruginosa up to 80-93% at 64 MIC within 24 h. The biofilm’s metabolite activities were also reduced to 77-93% within 24 h. Results of this study suggest that PA produced from palm kernel shell at optimum condition i.e. containing highest total phenolic contents, has good potential to be used for antibacterial and antibiofilm applications.